(a) Technical Field
The present disclosure relates to a method of controlling an environmentally-friendly vehicle, which controls a low voltage DC-DC converter (LDC) based on the state of an auxiliary battery of the vehicle and electric loads of the vehicle in order to maximize efficiency of the LDC of the environmentally-friendly vehicle.
(b) Description of the Related Art
As is well known, according to demands for improving the fuel efficiency of a vehicle and stronger on board diagnosis (OBD) regulations for exhaust gas, an environmentally-friendly vehicle has been provided.
An environmentally-friendly vehicle generally includes a fuel cell vehicle, an electric vehicle, a plug-in electric vehicle, and a hybrid vehicle, and includes one or more motors and engines.
The environmentally-friendly vehicle includes, for example, as illustrated in FIG. 1, a high voltage battery 20 for storing high voltage power for driving a motor 70, a bi-directional high voltage DC-DC converter (BHDC) 30 for converting a voltage input/output to/from the high voltage battery 20, an inverter 60, which is an electronic power control device, for converting a DC high voltage of the high voltage battery 20 to an AC voltage to drive the motor 70, a low voltage DC-DC converter (LDC) 50 for converting a DC high voltage to a DC low voltage to charge an auxiliary battery 40, a junction box 80, and various loads 90 for driving the environmentally-friendly vehicle.
The junction box 80 is disposed between the BHDC 30, the inverter 60, the LDC 50, and the various vehicle loads 90 to perform a connection therebetween.
The auxiliary battery 40 may be a battery of 12 V, and supplies power to components of the vehicle, for example, various electric loads of the vehicle, using a predetermined driving voltage.
Since the electric loads using the auxiliary battery 10 as a power source continuously consume power during the driving of the vehicle, the LDC 50 controls a power supply of the auxiliary battery 10 in order to charge the auxiliary battery 10.
The LDC 50 has an advantage in that conversion control is simple, and the LDC 50 is implemented with a small number of elements in general, whereby the LDC 50 is formed of a zero voltage switching (ZVS) full-bride pulse width modulation (PWM) circuit.
However, when a load is low or there is no load, ZVS fails, so that the entire efficiency of the LDC having the aforementioned configuration may deteriorate due to switching loss.
In order to solve the aforementioned problem in the related art, maximization of efficiency of the LDC is promoted by determining whether to operate the LDC and limiting an output current by comparing an output voltage of the LDC and a voltage of an auxiliary battery. However, the related art does not consider the state of the auxiliary battery, so that the life of the auxiliary battery may be decreased, and further, the auxiliary battery may be discharged in a case in which the load of a vehicle is sharply changed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.